The present invention relates to a molding apparatus for use in the production of a casting mold from a granular material and, more particularly, an apparatus wherein at least one pattern is positioned on a pattern plate within a mold frame wherein the granular molding material is received in the mold frame.
The packing of granular molding materials for the purpose of producing factory molds is well-known in the prior art. German Patent Specification No. 19 61 234 discloses a process for packing granular molding material wherein the packing of the molding material is effected by the expansion of a high pressure gas within the molding apparatus. In accordance with the process of the German Specification, air is stored in a reservoir over the molding box prior to the packing of the granular material. During the packing process the air, which is stored under pressure in the reservoir, is made to act on the surface of the molding material mass to be packed in the molding box. The large mass of air supplied during the packing process flows through the granular molding material and out openings provided in the molding box. It has been found that the air used in packing the molding material is sometimes compressed in the molding material mass which results in the mold having to be scrapped. It has been found that one critical region in which this undesirable compression takes place is between the pattern and the molding box wall.
Naturally, it would be highly desirable to design a mold apparatus which allows for precise evacuation of the high pressure gas used for packing the granular molding material which would eliminate the selective compression of gas in critical regions of the molding mass material thus resulting in having to scrap the resulting mold.
Accordingly, it is the principal feature of the present invention to design a mold apparatus having an improved gas outflow pattern.
It is a particular object of the present invention to provide an outflow arrangement between the pattern and the mold box wall so as to eliminate the necessity of mold scrapping and thereby increase mold strength values.
Further objects and advantages of the present invention will appear hereinbelow.